Vacatur of a probate decree in New York is an extraordinary remedy that disrupts the orderly administration of estates. Given that public policy and judicial economy disfavor post-probate will contests and, more generally, inefficiency in the administration of estates, New York courts have applied heightened standards in vacatur proceedings, requiring parties seeking such relief to do much more than merely allege facts which might be sufficient to question a probated instrument's validity. This article addresses the standards applied by the courts in granting and denying vacatur; the parties' entitlement to pre-vacatur disclosure and evidentiary hearings; the affirmative defenses that may be available in opposition to a vacatur application; and the countervailing policy interests that arise when the instrument in question contains an in terrorem clause.Practitioners should consider the standards for vacatur, entitlement to discovery and evidentiary hearings, and affirmative defenses that may be available when advising their clients as how to best make--or, for equal measure, oppose--a vacatur application.